Tension-controlling means for traveling offset webs



March 17, 1931. c. s. COTTRELL, 3D 1,796,331

TENSION CONTROLLING MEANS FOR TRAVELING OFFSET WEBS Filed March 21, 1930 INVENTOR M W 31:1

M44 ATTQRNEYS I In rotary multicolor web meme Mar, 17, 1931 antral PATENT OFFICE CALVERT IB- COTTRELL, 8B, OF WESTEBLY, RHODE ISLAND, ASSIGNOR T0 0. 1B. CQTTBELL & SONS COMPANY, 01 WESTEBLLY, RHODE ISLAND, A CORPORATION OF DELAWARE TEHSIUN-CONI'BOLLING MEANS FOR TRAVELING OFFSET WEBB Application filed larch 21, 1930. Serial No. 437,819.

ing presses where a tra eling oflset web is passed around the impression c linder of the second printin unit under t e printed web, it has been d' cult to obtain clean and sharp printin i If this tenslon on the offset web, necessary to the proper rewinding thereof, be eliminated where the oil'set web is in contact with the impression cylinder, the ofi'set web and the printed web will travel together around the impression cylinder, thereby en suring clean and sharp printing by the second printing unit.

The object of my invention is to accomplish this result by providing automatic means for maintaining a predetermined amount'of slack in and tension on the ofiset web between the impression cylinder of the second printing unit of the printing press and the tension control rolls of the offset web tension controlling mechanism for the rewinding mechanism.

The means which'I have shown for accomplishing this result includes a variable speed electric motor independent of the driving means for the printing press, said motor being utilized for driving the offset web tension control rolls and the rewindin rolls at the desired speeds, the speed of e motor being controlled by the position of the ofiset web slack roll through. a suitable controller in the motor circuit.

In ractice, the travel of th ,rinted web per 0 'nder revolution varies wit the difierent orms used on the form 0 linders, thus making it practically impossib e to pro rly proportion the tension control rolls 0 the ofiset web controlling mechanism so that they will travel with the ofiset web under all conditions. It is to prevent this variation from disturbing the travel of the offset web on the impression cylinder that I interpose the means for automatically maintaining a predetermined amount of slack in and tension on the offset web between the impression cylinder of the second printing unit and the said tension control rollst A practical embodiment of my invention is represented in the accompanying drawings,

rfecting printin which the form and impression cylinders 1, 2 and 3, which cylinders are driven in the usual manner. The traveling printed web is denoted by 4 and it is shown as being led around the idler roll 5 to and around. the im pression cylinder 3 and from thence to and beyond the idler roll 6. film traveling ollset web is denoted by 7 and it is shown as leading from its sup ly roll over the idler rolls 8 to and aroun the impression cylinder 3 and under the printed web at. From thence the offset web is shown as passing around the positively driven guide roll 9 and under the slack roller 10 where the slack in the web is formed, to and around the positively driven tension control rolls 11, 12 and 13 of the offset web tension controlling mechanism. From thence the client web lm' i tl-l around the idler rolls 14, 15 and 16 to the take-up roll 1'7 which rests upon and, is driven by the re windin rolls 18, 19 of the oflset web rewinding mec ianism.

The guide roll 9 is shown as being driven from the impression cylinder gear 530 at sub stantially the surface speed of the impression cylinder through the train of gears 21, 22, 23 24, 25.

lhe tension control rolls 11, 12 and 13 of the offset web tension controlling mechanism are shown as driven from a variable speed electric motor 26 entirely independent of the driving means for the printing press. In. the present instance these tension control rbfis 11, 12 and 13 are driven in unison through the gears 27, 28, 29. The rewinding rolls 18, 19 are driven from the tension control rolls at a slightly greater surface speed than the surface speed of the tension control rolls from the gear 29 through the train of gears 30, 31,32, 33, 34. The tension control rolls and thereby the rewinding rolls are driven from the motor 26 in the present in stance through a belt and pulley connection 35, 36, 37 between the motor and tcnsiini. con trol roll .tflpredetcrmined omit if mania; in tluai offset web between the second rinting unit and the tension controlling meow anism is anof the second printing un1t are denoted. by

H ll

tomatically maintained b varying the speed of the motor 26 and there y the surface speed ff the tension control rolls 11, 12, 13, as folows:

The offset web slack roller 10 is mounted in a rocking support 38, to which sup ort one end of a sprocket chain 39 is attache which chain passes over a sprocket 40 on the shaft 41 and is provided at its other end with a weight 42 for substantially counterbalancing the weight of the roller 10 and its rocking support. A gear 43 is fast on the shaft 41 and meshes with a pinion 44, fast on the shaft 45, which carries the arm 46 of a controller or rheostat 47 which is located in the electric circuit, denoted by 48, of the motor 26.

The predetermined tension is maintained on the offset web slack between the second printing unit and the web tension controlling mechanism as follows:

A roller 49 bears on the offset web as it passes over the first tension control roll 11, with sufficient ressure to eliminate any slippage of the web as it passes throu h the web tension controlling mechanism. s the only tension exerted on the web slack is formed by the pressure of the web slack roller' 10 thereon, this tension can be easily regulated by 1ncreasing or diminishing the effect of the counterbalanced weight 42 on the said roller.

The operation is as follows:

As the normal slack in the offset web increases the slack roller 10 will drop; thereby, through the chain, sprocket and gearing, cause the rheostat arm 46 to travel over its contact points in a direction to speed up the motor 26 and thereby increase the surface speed of the tension rolls 11, 12 and 13, and

also correspondingly increase the surface speed of the rewinding rolls 18, 19. As the extra slack in the offset web is taken up, the rheostat arm 46 returns to its previous normal osition in which the motor 26 is driven at su tantially the speed of the press. Reversely, as the normal slack in the web decreases, the slack roller 10 is raised, thereby causing the rheostat arm 46 to travel over its contact points in a direction to reduce the speed of the motor 26 and thereby the relative surface speeds of the tension control rolls 11, 12, 13 and the rewinding rolls 18, 19, until the normal slack in the offset web is obtained and the contact arm 46 returned to its normal intermediate osition.

From the a ve description it will be seen that a predetermined amount of slack and tension may be artomatically maintained in and on the offset web at all times, thereby ensuring clean and sharp printing by the second printing unit. i

It is evident that various changes may be resorted to in the construction, form and arrangement of the several parts without departing from the spirit and scope of m invention, and hence I do not intend to imit myself to the particular embodiment herein shown and described, but

What I claim is 1. In a multicolor web perfecting printing press, a printing unit, a traveling ofi'set web,-

a web tension controlling mechanism, an offset web rewinding mechanism, and automatic means for maintaining a predetermined amount of web slack and tension thereon between the printing unit and tension control- .ling mechanism, said automatic means including a variable speed motor for driving boththe web tension controlling mechanism and the offset web rewinding mechanism.

2. In a multicolor web perfecting printing press, a printing unit, a traveling offset web, a web tension controlling mechanism, an offset web rewinding mechanism driven therefrom, and automatic means for maintaining a predetermined amount of web slack and tension thereon between the printing unit and tension controlling mechanism.

3. In a multicolor web perfecting printing press, a printing unit, a traveling offset web, a web tension controlling mechamsm, an offset web rewinding mechanism driven therefrom, and automatic means for maintaining a predetermined amount of web slack and tension thereon between the printin unit and tension controlling mechanism, sai automatic means including a variable speed motor for driving the web tension controlling mechanism and thereby the offset web rewinding mechanism.

4. In a multicolor web perfecting printing press, a printing unit, a traveling ofi'set web, a web tension controlling mechanism, an offset web rewinding mechanism driven therefrom, and web slack controlled means for automatically maintaining a predeter mined amount of slack in and tension on the ofiset web between the printing unit and tension controlling mechanism.

5. In a multicolor web perfecting rinting press, a printing unit, a traveling 0 set web, a web tension controlling mechanism, an offset web rewinding mechanism, and automatic means for maintaining a predetermined amount of slack in and tension on the offset web between the printing unit and tension controlling mechanism, said automatic means including a variable speedmotor for driving both the web tension controlling mechanism and the offset web rewinding mechanism.

6. In a multicolor web perfecting printing press, a printing unit, a traveling offset web, a web tension controlling mechanism, an offset web rewinding mechanism, and automatic means for maintaining a predetermined amount of slack in and tension on the offset web between the printing unit and tension controlling mechanism, said automatic means including a variable speed motor fordriving both the web tension controlling mechanism all) and the ofl'set web rewinding mechanism and also including a web slack roller for controlling the s eed of the motor.

7. In a mu ticolor web perfecting rinting press, a printing unit, a traveling 0 set web, a web tension controlling mechanism, an oilset web rewinding mechanism, and ailtomatic means for maintaining a predetermined amount of slack in and tension on the offset web between the printing unit and tension controlling mechanism, said automatic means including a variable speed motor for driving both the web tension controlling mechanism and the offset web rewinding mechanismtand also including a web slack roller and a rheostat operated thereby for varying the s eed of the motor.

8. In a mu ticolor web perfecting flprinting press, a printing unit, a traveling 0 set web, a web tension controlling mechanism, an offset web rewinding mechanism driven therefrom, and automatic means for maintaining a predetermined amount of slack in and tension on the offset web between the print-in unit and tension controlled mechanism, sai means includin a variable speed motor for driving the we tension controlling mechanism and thereby the offset web rewinding mechanism.

9. In a multicolor web perfecting fiprinting press, a printing unit, a traveling 0 set web, a web tension controlling mechanism, an offset web rewinding mechanism driven therefrom, and automatic means for maintaining a predetermined amount of slack in and tension on the offset web between the printing unit and tension controlled mechanism, said automatic means includin a variable speed motor for driving the we tension controlling mechanism and thereby the offset web rewinding mechanism and also including a web slack roller for controlling the speed of the motor.

10.. In a multicolor web perfecting printing press, a printing unit, a traveling offset web, a web tension controlling mechanism, an offset web rewinding mechanism driven therefrom, and automatic means for maintaining apredetermined amount of slack in and tension on the oflt'set web between the printing unit and tension controlled mechanism, said automatic means including a variable speed motor for driving the web tension controlling mechanism and thereby the olfset web rewinding mechanism and also including a web slack roller and a rheostat operated thereby for varying the speed of tween the printing unit and the tension control rolls.

12. In a multicolor web perfectingprintin press, a printing unit, a traveling ofi'set we web tension control rolls, offset web rewinding rolls driven therefrom, and web slack controlled means for automatically maintaining a predetermined amount of slack in and tension on the offset web between the printing unit and the tension control rolls, said means including a variable speed motor for driving the tension control rolls and thereby the web rewindin rolls.

13. In a multicolor web per ecting printin press, a printing unit, a traveling offset we web tension control rolls, ofiset web rewinding rolls driven therefrom, and web slack controlled means for automatically maintaining a predetermined amount of slack in and tension on the offset web between the printing unit and the tension control rolls, said means including a variable speed motorfor driving the tension control rolls and thereby the web rewindin rolls and also including a web slack roller or controlling the speed of the motor.

14. In a multicolor web perfecting printin press, a printing unit, a traveling ofiset we web tension control rolls, offset web rewinding rolls driven therefrom, and web slack controlled means for automatically maintainin a predetermined amount of slack in an tension on the offset web between the printing unit and the tension control rolls, said means including a variable speed motor for driving the tension control rolls and thereby the web rewinding rolls and also including a web slack roller and a rheostat operated thereby for'varying the speed of the motor.

In testimony, that I claim the foregoing as my invention, I have signed my name this 14th day of March, 1930.

CALVERT B. COTTRELL, 31m. 

